Core and art of making same



(No Model.)

M. H. FLETCHER. GORE AND ART OF MAKING SAME.

Patented Mar. 2,1897.

Maul w Mame m: uanms FETERS o0. Maomum 0., wasnmo UNITED STATES PATENT OFFICE.

MORDECAI H. FLETCHER, OF CINCINNATI, OHIO.

CORE AND ART OF MAKING SAME.

I SPECIFICATION forming part of Letters Patent No. 578,080, dated March 2, 1897.

Application filed November 11, 1896. Serial No. 568,536. (No model.)

.To all whom it may concern.-

Be it known that LMORDEOAI H. FLETCHER, a citizen of the United States, residing at Oincinnati, Ohio, have invented new and useful Improvements in Cores and the Art of Making Same, of which the following is a specification.

My invention relates to cores for casting hollow articles where a core-bar or equivalent skeleton is employed as a basis upon which the ultimate core of loam, 85c. is built up, and is intended to provide a core embodying a combustible foundation for the loam upon the bar to be destroyed by the heat of the casting, so that the bar may be removed without interference from the shrinkage of the casting, and the cooling of the casting facilitated by allowing free access of air to the cast article. I

To this end my invention consists in an improved core for the casting of hollow articles of metal, such as pipe-sections, cylinders, &c. also in the constr uction and composition of a combustible foundation layer for the coating of loam or other earthy material placed upon a core-bar or other support, whereby the heat of the casting chars or practically destroys the foundation beneath the loam, thereby enabling the core-bar to be withdrawn without impediment from the shrinkage of the casting, and also allowing shrinkage to take place freely.

My invention as applied to cores for the manufacture of iron pipe is illustrated in the accompanying drawings.

Figure 1 is a partial sectional view of a pipefiask and mold, showing my improved core placed in the mold ready for the casting. Fig. 2 is a cross-section of the same in the plane 2 z of Fig. 1. Fig. 3 is an end elevation of a machine for forming and applying the combustible foundation to the core-bar.

In the manufacture of cast-iron pipe, cylinders, and other hollow articles the core generally consists of a central supporting-skeleton known as the core-bar, (which is generally a perforated metal tube,) upon which is built up the ultimate core in the following manner: First, the bar is wound about with a rope of hay or dried grass in adjacent coils from end to end. Upon this is applied alayer of moist clay material, which is dried by placing the bar in an oven. Upon the surface of the clay covering the rope is then built up the layer of loam, which, when suitably dressed and dried,constitutes the core proper, against which the molten metal is run, and which defines the interior surface and opening of the hollow article.

By the heat of the molten metal conducted through the loam and clay layers the hay rope is burned away, so as to permit the withdrawal of the core-bar as soon as the metal sets, Without which the shrinkage of the casting would bind the core-bar and endanger the casting, besides preventing removal of the bar. The removal of the core-bar also facilitates the cooling of the casting.

My improvement relates to the building up of composite cores, with similar objects in view, differing however in certain essential particulars, which efiect considerable saving of cost, labor, time, material, &c., besides improving the core itself and the pipe cast therefrom.

In building up the core Iproceed as follows: I first take a quantity of combustible matter, such, for example, as sawdust, ground leaves, ground straw, coarse Wood-pulp, or any material having the general characteristics of solidity and combustibility in a divided or comminuted state and treat the same with a fluid cementing agent, such, for example, as common starch mixed with water, which is "by heat converted into a highly adhesive semifluid mass, and in drying binds the solid particles together. I

In preparing the material for the layer I find it desirable to place in a suitable vat or tank a quantity of starch watera convenient proportion being (with a wide permissible va riation in either direction) fifty pounds of water to one of Starch -and apply heat to the boiling-point to convert the starch water into a semifluid paste with sufficient excess of water to allow for absorption of moisture by the sawdust or other material,which is then added and thoroughly mixed, so that the resulting product shall be of the semifluid consistency of thin mortar. erable method of applying the layer to the core-bar I take a flexible web or apron, of wire cloth or fabric having meshes sufficiently open to permit air to pass through freely,

Following then the prefspread upon it a layer of the plastic material so prepared, and wrap it around the bar with sufiicient pressure to force the layer uniformly into contact with the bar and express the excess of fluid material. A convenient apparatus for performing this operation commercially is shown in Fig. 3 and embodies the following construction:

In a suitable supporting-frame B are journaled two long rolls b 12 spaced apart sufficiently to receive between them the core-bar A, for which suitable j ournal-bearin gs are provided in the frame. A third roller 5 is carried below the others in the lower bight of an endless web or apron e and suitably guided in vertical slots of the frame.

Provision may be made for increasing the weight of the roll b as by weights or weighted levers Z, bearing upon its journals or the blocks in which they are carried.

The web 6 is preferablymade of wire-cloth, but any loosely-woven fabric or porous or perforated material of sufficient strength will answer the purpose. The web passes over the rollers b Z2 under the core-bar A, and is held taut by weight or downward pressure of the third roll 11 as indicated. The rolls 1) b are also preferably provided with means of adjustment, such as set-screws s 5 for increasing'or diminishing the distance between themselves and the core-bar A to regulate the thickness of the layer to be superimposed on the core-bar and to accommodate the varying diameters of the latter. The rolls Z) andthe intervening core-bar A are geared together by spur-gears f (indicated by dotted lines) to rotate in unison. A suitable catchbasincl is also provided for the liquid cement squeezed out of the layer, and thus prevents any waste. The core-bar being placed in position, asindicated, a quantity of the material in a semifluid state is placed upon a feed-in platen c and moved forward to or is otherwise deposited in a layer 00, of proper thickness, upon the webs at the upper side of the rollb, whence-it is'carried downward beneath and forced into contact with the core-bar A.

by the movement of the web 8. The described arrangement of the endless web and theaction of the suspended roll I) produce compression upon the layer m, by which its particles are forced into contact with each other and the layer into contact with the core-bar, and all surplus cement or paste is squeezedout and caught in the basin cl.

While other cementing agents maybe used,

purpose. In passing under the core-bar the web compresses the layer radially, squeezing out the excess of paste through the meshes of the web and causing the particles to adhere firmly to each other and the layer to adhere firmly to the core-bar. The thickness of the layer depends upon the quantity of material fed and its liquid consistency and the relative pressure produced by the weighted roll If, all of which may be varied to suit the particular case.

While I have thus described and shown apparatus for producing and attaching the layer which for commercial purposes I regard as the best, I do not confine myself to this or any other particular method or apparatus for the purpose.

The layer as applied to the bar is to bemade to adhere firmly to the bar. This may be done by transferring thecore-bar Atoadrying-oven, or the core-bar may be sufficiently heated previously to applying the coatingto dry the same without subsequent treatment, or the moisturemay be expelled by pressure. As soon as the combustible layer is sufficiently dry the final loam coating y is applied directly to the same and is then finished and dried in the usual mannerythe firm character of the combustible layer and theinequalities of thesurface constituting a secure holding for the loam without the intervening clay layer, such as used with the hay rope.

The heat of the casting practically destroys the combustible layer, enabling the core-bar to be withdrawn from the flask O with freedom as soon as the metal sets.

It will be sufficiently obvious thata wide range of materials may be res'ortedto-in forming the combustible layer. The solid matter may be any substance capableof being ground, shredded, or otherwise so comminuted as to form with thecementing agent a somewhat plastic mass to be applied as described and to bedried into a firmand adhesive layer adapted to receive and retain the loam coating and adapted, furthenrtobe destroyed as a solid mass by the heat of the casting.

Sawdust,comminuted leaves-twigs, stems, shrubs, grasses, straw,refuse: grain, or other vegetable matter or any combustible material may be used for the purpose, according to local conditions. There isalsoaconsiderable range of selection asto the cementing agent, sincewith' slight additional trouble'or expense many others, such as glues,-mucilaginous gums, 850., can be used with good practical results. What I have described, however, both as to material and method is deemed the best-under the conditions of cost and convenienceafter many experiments and successful results.

I claim as my invention and desire-to secure by Letters Patent of theUnitcdStates- 1. The improved core for castinghollow objects of metal, consisting of a metal core-bar, having applied thereto a concentric combus 10 With starch paste and applied to and dried upon a core-bar as an independent layer, substantiaily as set forth.

In testimony whereof I have hereunto set my hand in the presence of two subscribing Witnesses.

MORDEOAI H. FLETCHER.

Witnesses:

L. M. HOSEA, FRANK K. BOWMAN. 

